Then you'll be able to target your question precisely and have the most accurate answers.

I personally do experience slow connexion (browsing and package downloading) and it's due to a regression in drivers for my wifi card. The following lines fix it but I need to execute them every single time i start my computer up... So i made a script of this :

If you're just having trouble downloading the package named "quickly", then copy and paste the following code into a terminal:

sudo apt-get update
sudo apt-get -f install

This should solve the problem.
If it doesn't solve the problem, then run the following code in a terminal:

sudo dpkg --configure -a

If it still doesn't work, try to see if you have enough disk space left (1 GB or more). If you have less than 1 GB left, free up some space (or, if there is only 80 MB left, you'll have to redo the installation and accumulate your files elsewhere, even after the installation.)

If you have more than 1 GB of free space, follow the other solution posted.